1. Field of the Invention
The present invention relates to a cathode-ray display tube (hereinafter referred to as "CRT") for use with color printers, and more particularly to a CRT for use with color printers which has a display screen composed of three stripes of phosphor film which correspond to primary colors of red (R), green(G), and blue (B).
2. Prior Art
There has heretofore been known a CRT for color printers in which a light spot on the phosphor screen changes in position and color in response to input signals supplied for exposing photosensitive color paper to the light spot, the CRT being used for color facsimile and the like. The CRT utilizes, as with an ordinary CRT for color television sets, a blue-emitting phosphor, green-emitting phosphor, and a red-emitting phosphor for producing desired colors, and has a light-emitting characteristic as illustrated in FIG. 1 of the accompanying drawings. The graph of FIG. 1 has a horizontal axis respresenting wavelengths and a vertical axis representing relative intensities. Ordinary photosensitive color paper now available in quantities in the market inexpensively has a typical photosensitivity characteristic as illustrated in FIG. 2 of the accompanying drawings. A review of FIGS. 1 and 2 indicates that the light-emitting characteristic of the phosphors on CRT differs widely from the photosensitivity characteristic of the photosensitive paper. When the photosensitive paper is exposed to an image produced on CRT using such phosphors for color television, no picture image having a tone close to the original one will be reproduced on the color paper. As shown in FIG. 2, the ordinary color paper has widely different sensitivities to colors, a property which has prevented well-toned picture images from being reproduced on the paper.